Window that is only shown from a Beamer

I like to create a group game in a class room that I control from my application on my Mac.
All the displayed game windows that I want to show the people in the room should be displayed via a beamer to the audience (just these full-screen windows).
(And a small ‘feedback’ window would be shown in my application so that I don’t have to turnaround my head all the time). A bit like in a Powerpoint presentation.
So I reckon, I need somehow to tell which window is going to the beamer only, or is being mirrored.
Is there an Xojo example somewhere, or anyone has a nice and easy solution in mind?

Check Screen and ScreenCount in documentation.
You need to check coordinates there for the screens and maybe assign a window coordinates which move it to a specific screen.

NSScreenMBS may help, but you may again just see which is main screen (index 0), but what other screens are there and offer user the option to put windows always on second screen.

Here you have two related threads where I believe you can find useful information:

You mentioned powerpoint, and it got me thinking about my experience with it. I use a laptop connected to an external monitor but I only use the external monitor (single monitor) as output. When I run a powerpoint presentation it overrides my computer settings and in addition to displaying the presentation on my external monitor, it uses the laptop’s monitor to show the next slide (what you are attempting to do).

Using the method proposed by Christian (and which you can also find in the posts I linked above) you can’t reproduce what powerpoint is doing in my case (it’s a Windows macghine, btw), and you would need to setup your systems as having two screens first.